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IX. Conclusions on Temporary Abandonment, Kick Detection,

and the Emergency Response

A. Kick Detection and Response Failure Cause

At approximately 9:42 p.m., the crew detected flow and diverted the gas
influx from the well to the mud gas separator in accordance with the Transocean
well control manual. Shortly thereafter, the rig crew activated the upper annular
preventers and the upper variable bore ram, after mud ejected from the well was
already on the rig floor. The failure of the Deepwater Horizon crew (including
BP, Transocean, and Sperry‐Sun personnel) to detect the influx of
hydrocarbons until hydrocarbons were above the BOP stack was a cause of the
well control failure.

BP’s negative test procedures instructed personnel to monitor the well for
no flow and no pressure on the kill line. According to personnel monitoring the
well, the well was not flowing for 30 minutes and there was no pressure on the

kill line. But anomalies present during the negative tests, such as the presence of
drill pipe pressure when the kill line pressure was zero, should have prompted
the rig crew to investigate the results further. The Deepwater Horizon crew’s
(BP and Transocean) collective misinterpretation of the negative tests was a
cause of the well control failure.

B. Kick Detection Failure Contributing Causes

Pit volume (flow‐out) data is more accurate measure of flow than
calculating volume from pump output strokes and efficiency (flow‐in) and is the
preferred method for measuring flow. During critical cement testing, the crew
was using active pits number 9 and number 10 to transfer fluids to other pits,
while at the same time transferring fluids from the rig to the Damon Bankston.
Due to the activities onboard the Deepwater Horizon, the mudloggers were
concentrating on the flow‐out and flow‐in meters. The Deepwater Horizon
crew’s inability to accurately monitor pit levels while conducting
simultaneous operations during the critical negative test was a contributing
cause of the kick detection failure.

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